JP5824951B2 - Image forming apparatus and image forming system - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming system.

  Conventionally, in the image forming apparatus, in order to stabilize image quality, a plurality of image quality adjustment patterns with different image formation conditions are output, and image formation is performed based on detection results of the plurality of image quality adjustment patterns. As a technique configured to control the conditions, for example, those disclosed in Japanese Patent Application Laid-Open No. 2004-226482, Japanese Patent No. 4359051, Japanese Patent Application Laid-Open No. 2002-23562, and the like have already been proposed.

  An image forming apparatus according to Japanese Patent Application Laid-Open No. 2004-226482 includes an image carrier on which a visible image is formed, a primary transfer unit that transfers the visible image onto an intermediate transfer member, and a visible image on the intermediate transfer member. An image forming apparatus having a secondary transfer unit that transfers a transfer current adjustment image onto the recording material, and after transferring the transfer current adjustment image onto the recording material, Is provided with detection means for detecting the image density of the remaining toner, and the secondary transfer current is adjusted based on the density detection result.

Further, an image forming apparatus according to the above-mentioned Japanese Patent No. 4359051 is a pattern image forming unit that develops an electrostatic latent image obtained by electrophotographic exposure with toner and forms a pattern image on an image carrier;
A transfer means for transferring a pattern image from the image carrier to an intermediate transfer member by a first transfer roller, and transferring the pattern image from the intermediate transfer member to a recording paper by a second transfer roller via a recording paper carrier;
Fixing means for fixing an image on the recording paper;
A dedicated transfer roller for transferring a pattern image from the surface on which the pattern image is formed at a position facing the intermediate transfer member;
Detecting means for detecting a pattern image transferred to the dedicated transfer roller;
Control means for controlling the image characteristics based on the detection result of the detection means,
The dedicated transfer roller is provided so as to be able to come in contact with and separate from the surface on which the pattern image is formed, and is configured to come into contact with the surface when detecting the pattern image and away from the surface when not detecting.

  Furthermore, the image forming apparatus according to the above Japanese Patent Laid-Open No. 2002-23562 is an image forming apparatus that transfers an image formed on an image carrier onto a transfer material by the action of a transfer charging member to which a voltage is applied. An image presence / absence detection sensor for detecting whether or not an image is formed on a transfer material surface opposite to a surface to be transferred; and when an image is detected to be formed on the transfer material surface; And a control means for setting different control conditions when it is detected that no is formed.

Japanese Patent Laid-Open No. 2004-226482 Japanese Patent No. 4359051 JP 2002-23562 A

  By the way, the problem to be solved by the present invention is an image forming apparatus capable of adjusting the transferability of a single color image or a multicolor image formed so that at least a part thereof overlaps both sides of the recording medium. It is to provide a forming system.

  Also, the problem to be solved by the present invention is an image forming apparatus capable of adjusting the transferability of the image on the second surface under the condition where the case where the image is present on the first surface of the recording medium and the case where the image is not present is mixed. And providing an image forming system.

That is, the invention described in claim 1 includes an image holding body for holding a toner image,
Transfer means for transferring the toner image held on the image carrier onto a recording medium;
Fixing means for fixing the toner image transferred onto the recording medium by the transfer means;
A transport unit that transports the recording medium having the toner image fixed on the first surface by the fixing unit to the transfer unit again by inverting the first surface and the second surface of the recording medium;
A transferability detection toner image formed on the first surface of the recording medium and a transferability detection toner image formed on the second surface of the recording medium are combined with the first surface and the second surface of the recording medium. A transferability detecting toner image forming unit that forms a plurality of transfer units with different transfer conditions so that at least a part of the transfer unit overlaps the surface;
Density detection means for detecting the density in both the area overlapping and not overlapping with the transferability detection toner image on the first surface among the plurality of transferability detection toner images transferred to the second surface of the recording medium. When,
And a selection unit that selects a transfer condition in the transfer unit based on detection results in both the overlapping region and the non-overlapping region on the first surface of the density detection unit . An image forming apparatus.

Further, in the invention described in claim 2, the image carrier is an intermediate transfer member to which a plurality of toner images sequentially formed on a single or a plurality of photosensitive drums are transferred in a multiple manner.
2. The image forming apparatus according to claim 1, wherein the transferability detection toner image forming unit forms a plurality of transferability detection toner images with different transfer voltages applied to the transfer unit. .

  Furthermore, the invention described in claim 3 is characterized in that the transferability detecting toner image is composed of a single toner image and a multiple toner image obtained by superimposing a plurality of toner images. The image forming apparatus according to 1 or 2.

According to a fourth aspect of the invention, the transferability detecting toner image is formed on the first surface of the recording medium and the single toner image formed on the first surface of the recording medium. and multiple toner images superimposed a plurality of toner images, the part a single toner image formed on the first surface of the recording medium overlap, a single formed on the second surface of the recording medium and The multiple toner image and the multiple toner image formed on the first surface of the recording medium partially overlap each other, and are composed of single and multiple toner images formed on the second surface of the recording medium. An image forming apparatus according to any one of claims 1 to 3.

  Furthermore, the invention described in claim 5 is characterized in that the density detecting means detects the density of the transferability detecting toner image transferred and fixed on the recording medium. The image forming apparatus according to any one of the above.

  According to a sixth aspect of the present invention, the selection unit selects a transfer condition having the highest transfer image density from among the plurality of transferability detection toner images detected by the density detection unit. An image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

  Furthermore, in the invention described in claim 7, the selection unit sets a transfer condition in which the transfer density of both the single toner image for transferability detection and the multiple toner image detected by the density detection unit is the highest. The image forming apparatus according to claim 6, wherein the image forming apparatus is selected manually or automatically.

According to an eighth aspect of the present invention, there is provided an image holding body for holding a toner image,
Transfer means for transferring the toner image held on the image carrier onto a recording medium;
Fixing means for fixing the toner image transferred onto the recording medium by the transfer means;
A transport unit that transports the recording medium having the toner image fixed on the first surface by the fixing unit to the transfer unit again by inverting the first surface and the second surface of the recording medium;
A transferability detection toner image formed on the first surface of the recording medium and a transferability detection toner image formed on the second surface of the recording medium are combined with the first surface and the second surface of the recording medium. An image forming apparatus comprising: a transfer property detecting toner image forming unit that forms a plurality of different transfer conditions of the transfer unit so that at least a part thereof overlaps the surface;
Density detection means for detecting the density in both the area overlapping and not overlapping with the transferability detection toner image on the first surface among the plurality of transferability detection toner images transferred to the second surface of the recording medium. When,
A control device comprising: a selection unit that selects a transfer condition in the transfer unit based on detection results in both the overlapping region and the non-overlapping region of the first surface of the density detection unit . An image forming system characterized by the above.

  According to the first aspect of the present invention, it is possible to adjust the transferability of a single-color image or a multi-color image formed so that at least a part of both sides of the recording medium overlap each other.

  According to the second aspect of the present invention, when a single-color image or a multi-color image is transferred from the intermediate transfer member to both surfaces of the recording medium, the image transfer property can be adjusted.

  Furthermore, according to the third aspect of the present invention, it is possible to adjust the transferability of a single color image and a multicolor image formed so that at least a part thereof overlaps both sides of the recording medium.

  According to the fourth aspect of the present invention, it is possible to adjust the transferability of the single color image and the multiple color image transferred on both sides of the recording medium.

  Furthermore, according to the fifth aspect of the present invention, transferability can be adjusted based on the image finally formed on the recording medium.

  According to the sixth aspect of the present invention, when a single color image or a multicolor image is formed on both sides of the recording medium, the transferability of the image can be easily adjusted.

  Furthermore, according to the seventh aspect of the present invention, it is possible to satisfy both the transferability of the single color image and the multiple color image transferred on both sides of the recording medium.

  According to the invention described in claim 8, an image forming system capable of adjusting the transferability of a single-color image or a multi-color image formed so that at least a part thereof overlaps on both sides of the recording medium. Can be provided.

FIG. 1 is a block diagram showing a toner image for detecting transferability of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing the image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block diagram showing an image forming unit of the image forming apparatus according to Embodiment 1 of the present invention. FIG. 4 is a schematic diagram illustrating a toner image held on the intermediate transfer belt. FIG. 5 is a schematic diagram showing a toner image formed on a recording sheet. FIG. 6 is a graph showing the transfer voltage. FIG. 7 is a configuration diagram showing the secondary transfer unit. FIG. 8 is a schematic diagram showing a toner image formed on a recording sheet. FIG. 9 is a block diagram illustrating a control device of the image forming apparatus. FIG. 10 is a perspective configuration diagram showing a personal computer. FIG. 11 is a block diagram showing a personal computer. FIG. 12 is a configuration diagram showing the display unit. FIG. 13 is a block diagram showing the display unit. FIG. 14 is a block diagram showing a toner image for detecting transferability of the image forming apparatus according to Embodiment 1 of the present invention. FIG. 15 is a block diagram showing the display unit. FIG. 16 is a flowchart showing the operation of the image forming apparatus according to Embodiment 1 of the present invention. FIG. 17 is a configuration diagram showing the display unit. FIG. 18 is a configuration diagram showing the display unit. FIG. 19 is a flowchart showing the operation of the image forming apparatus according to Embodiment 1 of the present invention. FIG. 20 is a chart showing determination results of the image forming apparatus according to Embodiment 1 of the present invention. FIG. 21 is a block diagram showing an image forming unit of an image forming apparatus according to Embodiment 2 of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 is a schematic diagram showing a four-cycle color image forming apparatus as the image forming apparatus according to Embodiment 1 of the present invention. The color image forming apparatus includes an image reading device, and functions as a full-color copying machine and a facsimile, and also functions as a printer that forms an image based on image data output from a personal computer (not shown). . Further, as shown in FIG. 2, the image forming apparatus is connected to a personal computer 300 as a control device via a communication line 301, and can form an image based on image data output from the personal computer 300. In addition, the image quality can be adjusted based on a control signal from the personal computer 300.

  In FIG. 2, reference numeral 1 denotes a main body of the image forming apparatus. On the upper part of the main body 1 of the image forming apparatus, an automatic document sheet 2 is automatically conveyed to the image reading apparatus 4 in a state of being separated one by one. A document conveying device 3 and an image reading device 4 for reading an image of the document 2 conveyed by the automatic document conveying device 3 are arranged. The image reading device 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reduces a reflected light image from the document 2 including a full-rate mirror 7, half-rate mirrors 8 and 9, and an imaging lens 10. Scanning exposure is performed on an image reading element 11 made of a CCD or the like via an optical system, and the image reading element 11 reads an image of the document 2 at a predetermined dot density.

  The image of the document 2 read by the image reading device 4 is sent to the image processing device 12 as, for example, three-color image data of red (R), green (G), and blue (B) (each 8 bits), In this image processing apparatus 12, predetermined image such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color / moving editing, etc. are applied to the image data of the document 2 as necessary. Processing is performed, and the image data is converted into image data of four colors of yellow (Y), magenta (M), cyan (C), and black (K).

  The image data subjected to the predetermined image processing by the image processing device 12 as described above is an image corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K). Data is sequentially sent to the image exposure device 13, and the image exposure device 13 performs image exposure with laser light in accordance with the image data. The image forming apparatus is also configured to function as a printer. When the image forming apparatus functions as a printer, image data is input to the image processing apparatus 12 from a host computer 300 such as a personal computer. Then, after predetermined image processing is performed by the image processing device 12 as necessary, image data corresponding to the four colors is sequentially output to the image exposure device 13.

  For example, this embodiment is configured only by the image forming apparatus main body 1, but may be configured as an image forming system including the image forming apparatus main body 1 and a control device such as the host computer 300.

  An image forming unit 50 as an image forming unit capable of sequentially forming a plurality of toner images of different colors is disposed inside the image forming apparatus main body 1. The image forming unit 50 is roughly divided into a photosensitive drum 17 as an image holding body that holds a toner image, and a grid electrode as an example of a charging unit that charges the surface of the photosensitive drum 17 to a predetermined potential. A scorotron charging device 18 that is a corona charging device, and an image exposure device 13 as an electrostatic latent image forming unit that forms an electrostatic latent image according to image data by performing image exposure on the surface of the photosensitive drum 17. And rotary development as developing means capable of sequentially developing the electrostatic latent image formed on the surface of the photosensitive drum 17 with a plurality of toners having different colors to form a plurality of toner images having different colors. A device 19 and a cleaning device 20 as a cleaning means for cleaning the surface of the photosensitive drum 17 are provided. The charging means 18 is not limited to a corona charging device, and a roll-shaped charging member may be used.

  As shown in FIG. 3, the image exposure apparatus 13 modulates a semiconductor laser (not shown) according to image data, and emits a laser beam LB from the semiconductor laser according to image data. The laser beam LB emitted from the semiconductor laser is deflected and scanned by the rotary polygon mirror 14 and scanned and exposed to the surface of the photosensitive drum 17 as an image holding member via the f · θ lens 15 and the reflecting mirror 16.

  As shown in FIG. 2, the photosensitive drum 17 on which the laser beam LB is scanned and exposed by the image exposure device 13 has a predetermined speed (for example, 270 mm / sec or 110 mm) along a direction of an arrow by a driving unit (not shown). (Multiple speeds such as / sec).

  The surface of the photosensitive drum 17 is charged to a predetermined polarity (for example, negative polarity) and potential by a scorotron charging device 18 for primary charging, and then laser light LB is scanned and exposed according to image data. As a result, an electrostatic latent image corresponding to the image data is formed. The electrostatic latent image formed on the photosensitive drum 17 is developed in four color developing devices (developing means) 19Y, 19M, 19C of yellow (Y), magenta (M), cyan (C), and black (K). , 19K of the rotary developing device 19 rotatably provided, any one of the developing devices 19Y, 19M, 19C, 19K moves to a developing position facing the photosensitive drum 17, for example, a photosensitive member The toner image is reversely developed with a negatively charged toner having the same polarity as the charging polarity of the drum 17 to form a predetermined color toner image. The rotary developing device 19 is not limited to the four color developing devices 19Y, 19M, 19C, and 19K of yellow (Y), magenta (M), cyan (C), and black (K). Up to two developing devices 19 # 1 and 19 # 2 corresponding to toner (CT), light magenta (LM), and light cyan (LC) can be mounted as spares. At this time, image data corresponding to the transparent toner (CT), light magenta (LM), and light cyan (LC) is generated by the image processing device 12.

  As shown in FIG. 2, toner images of each color such as yellow (Y), magenta (M), cyan (C), black (K), etc., which are sequentially formed on the photosensitive drum 17, are formed on the photosensitive drum 17. Are transferred onto the intermediate transfer belt 21 composed of an endless belt as an intermediate transfer member disposed at the lower portion of the sheet by a primary transfer roll 22 as primary transfer means. The intermediate transfer belt 21 functions as an image holding body that holds the toner image transferred from the photosensitive drum. The intermediate transfer belt 21 includes a driving roll 23, a first driven roll 24a, a second driven roll 24b, a tension applying roll 24c, a third driven roll 24d, and an opposing roll 25 that constitutes a part of the secondary transfer unit. And is driven to circulate along the direction of the arrow at a speed substantially equal to the rotational speed of the photosensitive drum 17.

  On the intermediate transfer belt 21, yellow (Y), magenta (M), cyan (C), and black (K) are sequentially formed on the photosensitive drum 17 in accordance with the color of the image to be finally formed. The toner images of all or some of the four colors are transferred in a state of being sequentially superimposed by the primary transfer roll 22. The toner image transferred onto the intermediate transfer belt 21 is placed on a recording sheet 26 serving as a recording medium that is conveyed to a secondary transfer position at a predetermined timing, and a counter roll 25 that supports the intermediate transfer belt 21. Then, secondary transfer is collectively performed by a secondary transfer roll 27 as a secondary transfer unit that is in pressure contact with the opposing roll 25 via the intermediate transfer belt 21. As shown in FIG. 2, the recording paper 26 is of a desired size and material from any one of a plurality of paper feed cassettes 28, 29, 30 arranged in the lower part of the image forming apparatus main body 1. Paper is fed by paper feed rolls 28a, 29a, and 30a. From the plurality of paper feed cassettes 28, 29, and 30, paper of a desired material such as thick paper, coated paper, and thin paper can be fed in addition to plain paper. Note that the recording paper 26 such as plain paper, thick paper, coated paper, and thin paper is classified by basis weight. The fed recording paper 26 is transported to the secondary transfer position of the intermediate transfer belt 21 by a plurality of transport rolls 31 and 32 and a resist roll 33 at a predetermined timing. As described above, toner images of several predetermined colors are collectively transferred onto the recording sheet 26 from the intermediate transfer belt 21 by the opposing roll 25 and the secondary transfer roll 27.

  Further, the recording paper 26 on which the toner images of several predetermined colors are secondarily transferred from the intermediate transfer belt 21 is separated from the intermediate transfer belt 21 and then conveyed to the fixing device 35 by the conveyance belt 34. The unfixed toner image is fixed on the recording paper 26 by heat and pressure by the fixing device 35, and in the case of single-sided copying, it is discharged as it is onto the paper discharge tray 37 by the discharge roll 36, and a color image, a monochrome image, or the like. This image forming step is completed.

  The image forming apparatus is configured to be able to form images on both the front and back sides of the first and second surfaces of the recording paper 26, and a recording in which a toner image is fixed on the first surface by the fixing device 35. A double-sided conveyance unit is provided for conveying the paper 26 to the secondary transfer unit again by inverting the front and back of the recording paper 26.

  That is, when images are formed on both sides of the recording paper 26 in the image forming apparatus, the recording paper 26 having a color image or the like formed on the first surface (front surface) is discharged as it is as shown in FIG. Instead of being discharged onto the tray 37, the conveyance direction is changed downward by a reversing gate (not shown), and is once conveyed to a reversing path 40 by a conveying roll 38 and a reversing roll 39. Then, the recording paper 26 is conveyed to the double-sided passage 41 by the reversing roll 39 which is reversed this time, and is temporarily conveyed to the registration roll 33 by the conveying roll 42 provided in the double-sided passage 41. Then, the recording paper 26 is conveyed again by the registration roll 33 in synchronization with the toner image on the intermediate transfer belt 21, and the toner image transfer and fixing process is performed on the second surface (back surface) of the recording paper 26. After being performed, it is discharged onto the discharge tray 37.

  In this embodiment, the conveying roll 38 and the reversing roll 39, the reversing path 40, the double-sided path 41, and the conveying roll 42 constitute a double-sided conveying means. However, the present invention is not limited thereto, and any recording medium in which the toner image is fixed on the first surface by the fixing means may be used as long as the recording medium is reversed and conveyed to the transfer means again.

  In FIG. 2, reference numeral 43 denotes a manual feed tray for manually feeding the recording paper 26 having a desired size and material.

  FIG. 3 is a configuration diagram showing the image forming unit 50 of the image forming apparatus.

  In this image forming apparatus, as described above, after the surface of the photosensitive drum 17 is uniformly charged to a predetermined polarity and potential by the scorotron charging device 18 for primary charging, the surface of the photosensitive drum 17 is then charged. The image exposure device 13 sequentially exposes images corresponding to predetermined colors to form an electrostatic latent image.

  The electrostatic latent images sequentially formed corresponding to the respective colors on the surface of the photosensitive drum 17 as described above are developed by the corresponding color developing devices 19Y, 19M, 19C, and 19K as shown in FIG. A toner image T of a predetermined color is formed on the surface of the photosensitive drum 17.

  As shown in FIG. 3, the rotary developing device 19 includes yellow (Y), magenta (M), cyan (C), and black (K) developing devices 19Y, 19M, 19C, and 19K. The developing rollers 196 of the corresponding color developing devices 19Y, 19M, 19C, and 19K face the photosensitive drum 17 by rotating along the direction of the arrow about the rotation shaft 197. The electrostatic latent image formed on the surface of the photosensitive drum 17 is developed with toner of a desired color.

  As the developing devices 19Y, 19M, 19C, and 19K, as shown in FIG. 3, for example, a two-component developing device in which a two-component developer 192 composed of toner and carrier is accommodated in a developing device main body 191. Is used. Toner inside the developing device main body 191 is replenished from toner cartridges 193Y to 193K (see FIG. 2) at a predetermined timing, and the toner concentration in the developing device main body 191 is maintained within a predetermined range. It is configured as follows. The toner supplied to the inside of the developing device main body 191 is agitated with the developer 192 in the developing device main body 191 by the two agitators 194 and 195 for stirring and conveying the developer, is frictionally charged, and circulates. In the meantime, it is supplied to the developing roll 196 and conveyed to a developing region facing the surface of the photosensitive drum 17 as a magnetic brush of the developer 192 formed on the surface of the developing roll 196, and the surface of the photosensitive drum 17. It is used for development of the electrostatic latent image formed.

  For example, if the electrostatic latent image formed on the photosensitive drum 17 corresponds to a yellow color, the electrostatic latent image is developed by the yellow developing device 19Y and is applied to the photosensitive drum 17. In this case, a yellow toner image T is formed. For other magenta, cyan, and black colors, corresponding color toner images T are sequentially formed on the photosensitive drum 17 by the same process.

  The toner images T of the respective colors sequentially formed on the photosensitive drum 17 are primarily transferred from the photosensitive drum 17 to the surface of the intermediate transfer belt 21 at a primary transfer position where the photosensitive drum 17 and the intermediate transfer belt 21 are in contact with each other. Transcribed. At this primary transfer position, a primary transfer roll 22 is disposed on the back side of the intermediate transfer belt 21, and the intermediate transfer belt 21 is brought into contact with the surface of the photosensitive drum 17 by the primary transfer roll 22. . A voltage having a polarity (positive polarity) opposite to the charging polarity of the toner is applied to the primary transfer roll 22, and the toner image T formed on the photosensitive drum 17 is primarily transferred onto the intermediate transfer belt 21.

  In the case of forming a single color image, the toner image T of a predetermined color that is primarily transferred onto the intermediate transfer belt 21 is immediately secondary transferred onto the recording paper 26 at the secondary transfer position. In the case where a color image is formed by superimposing the toner images T, a toner image T of a predetermined color is formed on the photosensitive drum 17, and the toner image T is multiplexed on the intermediate transfer belt 21. The primary transfer process is repeated for a predetermined number of colors.

  For example, when a full color image is formed by superimposing four color toner images T of yellow (Y), magenta (M), cyan (C), and black (K), one of them is formed on the photosensitive drum 17. For each rotation, yellow (Y), magenta (M), cyan (C), and black (K) toner images T are sequentially formed. These four color toner images are superimposed on the intermediate transfer belt 21. In this state, the primary transfer is performed sequentially.

  Further, the toner remaining outside the primary transfer onto the intermediate transfer belt 21 from the photosensitive drum 17 and the external additive of the toner are gradually electrified by a pre-cleaning slow current device 44 as shown in FIG. Cleaning is performed by the cleaning device 20. The cleaning device 20 uses the cleaning brush 201 and the cleaning blade 202 to remove deposits such as toner and toner external additives remaining on the surface of the photosensitive drum 17, and the removed deposits of toner and the like are removed. It is configured to be discharged to the outside of the cleaning device 20 at a timing determined in advance by 203. Further, the surface of the photosensitive drum 17 cleaned by the cleaning device 20 is uniformly exposed and gradually charged by the slow power lamp 46 to prepare for the next image forming process.

Further, the intermediate transfer belt 21 rotates in a cycle synchronized with the photosensitive drum 17 while holding, for example, a yellow unfixed toner image T that is primarily transferred first, and on the intermediate transfer belt 21, As shown in FIG. 4, the magenta, cyan, and black unfixed toner images T _M , T _C , and T _K are sequentially superimposed on the single or yellow unfixed toner image T _Y for each rotation. It is transcribed in a state.

  The unfixed toner image T primarily transferred to the intermediate transfer belt 21 in this way is conveyed to a secondary transfer position facing the conveyance path of the recording paper 26 as the intermediate transfer belt 21 rotates.

  Then, as shown in FIG. 2, the recording paper 26 is fed from the desired paper feed cassettes 28, 29, 30 by the paper feed rolls 28a, 29a, 30a, and is registered by the transport rolls 31, 32, as described above. It is conveyed to the roll 33 and is fed between the pressure contact portions between the secondary transfer roll 27 and the intermediate transfer belt 21 by the registration roll 33 at a predetermined timing.

  Further, on the back side of the intermediate transfer belt 21 at the secondary transfer position, as shown in FIG. 3, a counter roll 25 that forms a counter electrode of the secondary transfer roll 27 is disposed. At the secondary transfer position, the secondary transfer roll 27 is always in pressure contact with the intermediate transfer belt 21, or the secondary transfer roll 27 is in pressure contact with the intermediate transfer belt 21 at a predetermined timing to contact the secondary transfer roll 27. By applying a voltage having a polarity opposite to the charging polarity of the toner, or applying a voltage having the same polarity as the charging polarity of the toner to the opposite roll 25, the undecided image transferred onto the intermediate transfer belt 21 serving as the toner image holding member. The toner image T is secondarily transferred onto the recording paper 26 at the secondary transfer position.

  In FIG. 3, reference numeral 49 denotes a belt cleaning device that cleans the surface of the intermediate transfer belt 21. The belt cleaning device 49 is usually separated from the surface of the intermediate transfer belt 21, It is configured to contact the surface of the transfer belt 21 at a predetermined timing.

  Then, the recording paper 26 onto which the unfixed toner image T has been transferred is peeled off from the intermediate transfer belt 21 as shown in FIG. 3, and the electrode member 47, the guide plate 48, and the conveyance member disposed downstream of the secondary transfer unit. The belt 34 is sent to a fixing device 35 (see FIG. 2) to fix the unfixed toner image T.

The intermediate transfer belt 21 has a volume resistivity of 10 ⁶ to 10 ¹⁴ Ω · cm by dispersing an appropriate amount of a conductive agent such as carbon black in synthetic resins such as polyimide and polyamideimide, or various rubbers. It is formed by the film-like belt adjusted as described above. The thickness of the intermediate transfer belt 21 is set to 0.1 mm, for example. The peripheral length of the intermediate transfer belt 21 is set to an integral multiple (for example, 2 to 3 times) the peripheral length of the photosensitive drum 17.

  Further, the secondary transfer roll 27 is disposed so as to be able to come into contact with and separate from the intermediate transfer belt 21 as necessary. When a color image is formed, the unfixed toner image T of the final color is intermediate. It is separated from the intermediate transfer belt 21 until it is primarily transferred onto the transfer belt 21. Note that the secondary transfer roll 27 may remain in contact with or separated from the intermediate transfer belt 21.

Further, the secondary transfer roll 27 includes an elastic layer made of urethane rubber or the like in which an ion conductive material is dispersed, for example, and the secondary transfer roll 27 has a volume resistivity of 10 for example. ^It is set to ³ to 10 ¹⁰ Ω · cm, the roll diameter is formed to be φ28 mm, and the hardness is set to 30 ° (Asker C hardness), for example.

On the other hand, the back support roll 25 includes an elastic layer made of EPDM rubber in which an ion conductive conductive material is dispersed. For example, the surface resistivity is 10 ⁷ to 10 ¹⁰ Ω / □, and the roll diameter Is set to φ28 mm, and the hardness is set to 70 ° (Asker C hardness), for example.

  Further, the electrode member 47 disposed downstream of the contact portion of the secondary transfer position is preferably a sheet metal as a conductive plate member, and in this embodiment, a stainless steel plate having a thickness of 0.5 mm is used. A recording paper 26 having a needle shape is used. Further, the tip of the electrode member 47 on the secondary transfer region side is, for example, 1 mm from the line formed by the nip portion of the back support roll 25 and the secondary transfer roll 27 on the secondary transfer roll 27 side, and the exit of the nip portion. More than 7 mm apart.

  By the way, in the image forming apparatus configured as described above, as shown in FIGS. 2 and 3, yellow (Y) and magenta (M) are formed on the photosensitive drum 17 in accordance with the color of the image finally formed. , Cyan (C), black (K), and the like are sequentially formed, and these toner images are primary-transferred on the intermediate transfer belt 21 singly or superimposed on each other as shown in FIG. After that, the image is secondarily transferred from the intermediate transfer belt 21 to the recording paper 26 and fixed, and an image of a desired color is formed.

For example, when forming a red (red) image, as shown in FIG. 4, a double color in which a yellow (Y) toner image _TY and a magenta (M) toner image _TM are superimposed. the toner in the toner image is formed, green in the case of forming an image of the (green) are yellow (Y) dual-color obtained by superimposing color toner images T _Y and cyan (C) toner image T _C of the image is formed, when forming an image of blue (blue), the magenta (M) toner image T _M and cyan (C) dual-color toner image obtained by superimposing color toner images T _C of the It is formed.

Further, even when forming an image of black (K), as shown in FIG. 4, the image of a single color is formed composed of a single color toner image T _K of black (K) by the user of the designated or images In addition to the above, a three-color toner image (so-called process black: PK) in which three color toner images T _Y , T _M , and T _C of yellow (Y), magenta (M), and cyan (C) are superimposed. May be formed.

  As shown in FIG. 4, the image held on the intermediate transfer belt 21 as an image holding member in this manner is a single color (single color) of yellow (Y), magenta (M), cyan (C), and black (K). 1) an image composed of the toner image T, a double color in which yellow (Y) and magenta (M) are superimposed, a double color in which yellow (Y) and magenta (M) are superimposed, and magenta (M) Various toners such as a double color obtained by superimposing cyan (C) or a triple color toner image obtained by superposing three toner images T of yellow (Y), magenta (M) and cyan (C) An image is formed, and the toner images held on the intermediate transfer belt 21 are collectively secondarily transferred onto the recording medium 26 by the secondary transfer roll 27 and fixed by the fixing device 35.

  FIG. 4 shows a toner image that has been primary-transferred multiple times on the intermediate transfer belt 21, and the toner image that has been secondary-transferred collectively from the intermediate transfer belt 21 onto the recording medium 26 is a toner of each color. The laminated state of the image is upside down.

  In the image forming apparatus, as shown in FIG. 2, the recording paper 26 having the image transferred and fixed on the first surface (front surface) 26a is conveyed again to the secondary transfer position with the front and back thereof reversed. The image is transferred and fixed on the second surface (back surface) 25 b of the recording paper 26, so that images can be formed on both surfaces of the recording paper 26. At this time, when the recording paper 26 having the image transferred and fixed on the first surface (front surface) passes through the secondary transfer position again, as shown in FIG. 5, the recording paper 26 is applied to the first surface (front surface) 26a of the recording paper 26. When the image has already been transferred and fixed, and the image is secondarily transferred to the second surface (back surface) 26 b of the recording paper 26, the transfer condition is to transfer the image to the first surface (front surface) 26 a of the recording paper 26. It may be different from the case.

  At that time, on the recording paper 26, as shown in FIG. 5, the toner image formed on the first surface (front surface) 26a and the toner image formed on the second surface (back surface) 26b do not overlap. And some or all of them may overlap. In addition, even when the toner image formed on the first surface (front surface) 26a and the toner image 26b formed on the second surface (back surface) overlap, the single-layer toner images overlap each other; There are various cases, such as a case where a single-layer toner image and a multi-layer toner image overlap each other, and a case where a multi-layer toner image overlaps, and recording is performed from the intermediate transfer belt 21 depending on the formation state of each of these toner images. The transfer states of the toner images that are secondarily transferred onto the medium 26 are different.

Therefore, in this embodiment, as shown in FIG. 1, a special toner image 100 for detecting transferability is used as a toner image for detecting transferability in the image forming apparatus. The toner image 100 for detecting transferability is, for example, a three-color toner of, for example, yellow (Y), magenta (M), and cyan (C) on the first surface (front surface) 26a of the A3 size recording paper 26. toner images of triple color density 100% superimposed image T (the process K) 101, the concentration 100 superimposed yellow (Y) toner image T _Y and magenta (M) toner image T _M of % of the toner image 102 of the dual-color red (red), yellow (Y) toner image T _Y and cyan (C) toner image T _C a superimposed concentration of 100% of the dual-color green of A (blue) toner image 103, a magenta (M) toner image T _M, and a cyan (C) toner image T _C are superimposed on a 100% density double color blue (blue) toner image 104. And a black (K) monochromatic toner image 10 having a density of 100%. A magenta (M) single-color toner image 106 having a density of 60%, a cyan (C) single-color toner image 107 having a density of 60%, and a black (K) toner image 108 having a density of 60%. It is formed.

  The recording paper 26 on which the transferability detecting toner image 100 is formed is not limited to the A3 size recording paper 26. For example, the recording paper 26 is formed on a plurality of A4 size recording papers 26 such as two sheets. The size and number of sheets are arbitrary.

  As shown in FIG. 1, the toner images 101 to 108 of these colors are formed in a square shape such as 10 to 20 mm square and have predetermined intervals G1 and G2 along the vertical and horizontal directions (in the example shown, G1 = G2). However, the shape, size, and interval such as a rectangular shape are arbitrary.

Further, as shown in FIG. 1, the toner images of the respective colors have a transfer voltage applied to the secondary transfer roll 27 when the toner image formed on the intermediate transfer belt 21 is transferred onto the recording paper 26. Along the conveyance direction A of the recording paper 26, in a direction crossing the conveyance direction of the intermediate transfer belt 21 with reference to a standard transfer voltage V ₀ automatically determined according to the thickness of the recording paper 26 and the like. Each set of toner images 101 to 108 along the line is secondarily transferred from the intermediate transfer belt 21 onto the recording paper 26 in a state where the toner images 101 to 108 are changed in a negative direction and a positive direction over a plurality of levels (16 levels in the illustrated example). The

In this embodiment, as shown in FIG. 6, when the transfer voltage applied to the secondary transfer roll 27 is set to the standard transfer voltage V _2nd as the index “0”, the standard transfer voltage V _{0 is set} to 10 The transfer voltage V decreased by% is changed in 5 steps in the negative direction to the transfer voltage V- ₅ , and the transfer voltage V increased by 10% in increments of the standard transfer voltage V is increased in the positive direction to the transfer voltage V _{+ 10.} It is configured to change over 10 stages (16 stages in total). The value for changing the transfer voltage applied to the secondary transfer roll 27 is not limited to 10% and 16 steps, and may be more or less than this. There is no need to change at intervals.

As shown in FIG. 7, the transfer voltage V _2nd applied to the secondary transfer roll 27 is the system resistance R _{SYS of the} secondary transfer portion comprising the back support roll 25, the intermediate transfer belt 21, and the secondary transfer roll 27. And the transfer current I.

As a result, in this embodiment, as shown in FIG. 1, the first surface (front surface) of the A3 size recording paper 26 has a process K101 _{-5 to} 101 _{+10 having} a density of 100% and a red having a density of 100%. (Red) 102 _{-5 to} 102 ₊₁₀ , green 100% density 103 _{-5 to} 103 ₊₁₀ , blue 100% density 104 _{-5 to} 104 ₊₁₀ , black 100% density (K ) 105 _{-5 to} 105 ₊₁₀ , 60% density magenta (M) 106 _{-5 to} 106 ₊₁₀ , density 60% cyan (C) 107 _{-5 to} 107 ₊₁₀ , density 60% black (K ) Eight types of 108 _{−5 to} 108 ₊₁₀ , 16 stages, a total of 128 toner images are formed.

On the other hand, on the second surface (back surface) 26b of the recording paper 26, as shown in FIG. 1, a total of 128 toner images 101 _{−, which} are the same as the toner images formed on the first surface (front surface) of the recording paper 26, are formed. _{5 to} 101 ₊₁₀ , 102 _{-5 to} 102 ₊₁₀ , 103 _{-5 to} 103 ₊₁₀ , 104 _{-5 to} 104 ₊₁₀ , 105 _{-5 to} 105 ₊₁₀ , 106 _{-5 to} 106 ₊₁₀ , 107 _-5 to 107 ₊₁₀ , 108 _{-5 to} 108 ₊₁₀ are formed. However, the 128 toner images formed on the second surface (back surface) 26b of the recording paper 26 are in the main scanning direction with respect to the toner images formed on the first surface (front surface) 26a of the recording paper 26. It is formed in a state in which the position is shifted by half the width of one toner image along a direction intersecting the moving direction of a certain intermediate transfer belt 21.

  Therefore, the toner image formed on the first surface (front surface) of the recording paper 26 and the toner image formed on the second surface (back surface) of the recording paper 26 are as shown in FIG. The width of the remaining half of the toner image is formed on the first surface (front surface) 26a of the recording paper 26 and the second surface (back surface) 26b of the recording paper 26. The toner images are formed so as not to overlap each other and exist independently.

  In this way, the toner image formed on the first surface (front surface) 26a of the recording paper 26 and the toner image formed on the second surface (back surface) 26b of the recording paper 26 are shifted by a half width. In this case, it is desirable that the space for forming a plurality of toner images can be set small by the overlapping amount.

  However, when the toner image formed on the first surface (front surface) 26a of the recording paper 26 and the toner image formed on the second surface (back surface) 26b of the recording paper 26 are shifted by a half width. As shown in FIG. 8B, the toner image formed on the first surface (front surface) of the recording paper 26 and the toner image formed on the second surface (back surface) of the recording paper 26 are not limited thereto. Of course, the completely overlapped image and the image where they do not completely overlap may be completely separated and formed separately. Further, the shift amount is not limited to the half width of the toner image, and may be set to another value.

  The toner image formed on the first surface (front surface) 26a of the recording paper 26 and the toner image formed on the second surface (back surface) 26b of the recording paper 26 are in the vertical direction (moving direction of the intermediate transfer belt). And the horizontal direction (direction intersecting with the moving direction of the intermediate transfer belt) are formed at predetermined intervals G1 and G2 at the same interval on the front and back sides. The writing positions L1 and L2 along the direction intersecting the direction are formed so as to be shifted so that the back surface side becomes larger by half the width of the toner image.

  Further, in this embodiment, as shown in FIG. 2, the recording paper 26 is reversed by using the reversing passage 40 to reverse the conveyance direction of the recording paper 26. The leading edge of the first surface (front surface) and the leading edge of the second surface (back surface) of the recording paper 26 are in opposite directions. Therefore, in this embodiment, as shown in FIG. 1, the positions L3 and L4 for forming 128 toner images are set to positions having the same length from the leading edge and the trailing edge of the recording paper 26. The positions of the toner images formed on the first surface (front surface) and the second surface (back surface) of the paper 26 along the transport direction of the recording paper 26 are set to be the same position (L3 = L4) and overlap each other. Has been.

  Further, the positions along the direction (main scanning direction) of the toner image formed on the first surface (front surface) 26a and the second surface (back surface) 26b of the recording paper 26 intersect the conveyance direction of the recording paper 26, respectively. The timing at which image exposure is started by the image exposure device 13 is set by shifting the timing corresponding to half the width of the toner image.

  FIG. 9 is a block diagram showing a control circuit of the image forming apparatus according to this embodiment.

  In FIG. 9, reference numeral 200 denotes a control device that controls the operation of the image forming apparatus. The control device 200 includes a control circuit 201 including a CPU that controls the operation of the image forming apparatus, and the operation of the image forming apparatus. A storage unit 202 for storing programs and parameters for controlling the image, an input / output control unit 203 for controlling signal input / output, and transferability detection forming means for forming a toner image 100 for transferability detection A transferability detecting toner image forming unit 204 that stores image data as The transferability detection toner image forming unit 204 includes image data stored to form a transferability detection toner image 100 as shown in FIG.

  Further, as shown in FIG. 9, the control circuit 201 controls the image forming unit 50 via the input / output control unit 203 and also applies the transfer voltage applied to the secondary transfer roll 27 via the high-voltage power supply circuit 110. The constant voltage control is performed to a plurality of predetermined values.

  Furthermore, as shown in FIG. 9, the control circuit 201 receives image data read by the image reading device 4 via the input / output control unit 203, is temporarily stored in the storage unit 202, and is also input / output. User setting data such as the size of the recording paper 26 and the number of prints input from the operation unit 205 which also functions as a selection unit are input via the control unit 203.

  FIG. 10 shows a modified example of this embodiment, and functions as a control device when an image forming system in which the image forming apparatus main body 1 and a control device 300 such as a personal computer are combined as shown in FIG. 2 is a configuration diagram showing a personal computer 300. FIG.

  As shown in FIG. 10, the personal computer 300 includes a personal computer main body 310, a keyboard 311 and a mouse 312 that also function as selection means for operating the personal computer 300, a liquid crystal display device 313 as a display device, and the like. As shown in FIG. 11, the personal computer main body 310 includes a CPU 301, a ROM 302, a RAM 303, an interface unit 304, a system bus 305 for connecting them, and the like.

As shown in FIG. 10, the personal computer 300 includes a pen-type manually operated colorimeter 314 connected to the personal computer main body 310 via a USB terminal or the like. The manual operation type colorimeter 314 is for reading an image on the recording paper 26 on which the transferability detecting toner image 100 is formed, for example, with a color system of L ^* a ^* b ^* .

  The CPU 301 controls the entire personal computer 300 via the system bus 305. The ROM 302 stores a program for the CPU 301. Examples of the program stored in the ROM 302 of this embodiment include a program as a printer driver that controls the image forming apparatus main body 1 that functions as a printer, in addition to a program that provides a function equivalent to a so-called operating system. A RAM 303 is configured by an SRAM or the like, and stores program control variables, data for various processes, and the like.

  The interface unit 304 is for communicating with the external image forming apparatus main body 1 and the like.

  With the above configuration, the image forming apparatus according to this embodiment can adjust the image transferability when a single-color image or a multi-color image is formed on both sides of the recording medium as follows. It has become.

That is, in the image forming apparatus according to this embodiment, as shown in FIG. 9, for example, a user or a service engineer operates the operation unit 205 as a user interface, and the display screen 400 of the operation unit 205 displays FIG. As shown in FIG. 12A, the “spec setting / registration” button is pressed in the machine manager mode, and as shown in FIGS. 12B and 12C, the recording paper 26 used by the user when evaluating transferability. Select the type and mass. The types of recording paper 26 that the user desires to use include the type of uncoated paper or coated paper, and the weight of the paper, for example, the weight of uncoated paper is 64 to 80 g / m ² . if coated paper, its mass ^{106~128g / m 2, 129~150g / m} 2, 151~176g / m 2, ··· , etc. are inputted is set.

  Next, in the operation unit 205, as shown in FIGS. 13A and 13B, a transfer output adjustment operation for outputting the transferability detecting toner image 100 is performed, and a value for changing the transfer voltage, etc. Is entered.

  Finally, in the operation unit 205, as shown in FIG. 13C, after all setting items for outputting the transferability detecting toner image 100 are set, the determination button 402 is pressed, and the user selects The setting operation for outputting the transferability detecting toner image 100 on the designated recording paper 26 ends.

  In the operation unit 205, when the confirmation print button 403 is operated as shown in FIG. 13C, the image forming apparatus main body 1 executes the output operation of the transferability detecting toner image 100, and FIG. Then, a transferability detecting toner image 100 as shown in FIG. 14 is output.

  The transferability detection toner image 100 output from the image forming apparatus main body 1 is optionally provided to the image reading apparatus 4 or the personal computer 300 attached to the image forming apparatus main body 1 as shown in FIG. Scanning is performed using a manually operated colorimeter 314 connected thereto. When reading the toner image 100 for transferability detection using the manually operated colorimeter 314, as shown in FIG. 14, the manually operated colorimeter 314 is arranged at the reading start position, and the reading button While pressing, the manually operated colorimeter 314 is moved in the vertical direction along the process black toner image 101 or the monochrome black (K) toner image 104 of the transferability detecting toner image 100. The toner image 100 for detecting transferability of each color is read for each column.

  The density data of the transferability detecting toner image 100 read by the manual operation type colorimeter 314 or the image reading device 4 is arithmetically processed by a CPU or a control circuit to produce a graph as shown in FIG. The

  As shown in FIG. 16, the CPU 301 or the control circuit 201 determines the maximum value of the detected density of the black single-color toner image and the maximum density of an image whose density is low by a predetermined threshold from the maximum value, for example, 0.05. In addition to obtaining the area, a maximum value of the detected density of the triple-color toner image and a maximum density area of an image whose density is lower than the maximum value by a predetermined value, for example, 0.05 are obtained (step 101).

  Next, the CPU 301 or the control circuit 201 determines whether or not there is an overlapping area between the highest density area of the black single color toner image and the highest density area of the triple color toner image (step 102). If there is an overlapping area between the highest density area of the single color toner image and the highest density area of the triple color toner image, it is determined whether or not there is one overlapping area (step 103). If there is one overlapping area, the one area is determined as a recommended value for the transfer voltage (step 104), and the recommended value determination flow is terminated. If there are a plurality of overlapping areas, it is determined whether or not the process black (K) has the smallest setting value among the overlapping areas (step 106). If the process black (K) has the smallest setting value, the second smallest value in the overlapping area is determined as the recommended value (step 107), and the recommended value determination flow ends. To do. On the other hand, if the process black (K) has the smallest setting value in the overlapping area, the minimum value in the overlapping area is determined as a recommended value (step 108), and the recommended value is determined. End the flow.

  When the CPU 301 or the control circuit 201 determines that there is no overlapping area between the highest density area of the black single-color toner image and the highest density area of the triple-color toner image, the process black (K) It is determined whether or not there are a plurality of regions (step 109). If there are not a plurality of process black (K) regions, the one region is determined as a recommended transfer voltage value (step 110), and the recommended value is determined. End the decision flow. Further, when there are a plurality of process black (K) areas, the second smallest value among the plurality of overlapping areas is determined as a recommended value (step 111), and the recommended value determination flow is terminated.

  As shown in FIGS. 17 and 18, the CPU 301 or the control circuit 201 performs the same process on the transfer paper detection toner image 100 formed on the second surface of the recording paper 26. The process is executed in a region where the transferability detecting toner image 100 formed on one surface is present and a region where the toner image 100 is not present.

  Then, the CPU 301 or the control circuit 201 is formed on the first surface of the recording paper 26 with respect to the transferability detecting toner image 100 formed on the second surface of the recording paper 26 as shown in FIG. It is determined whether or not there is an overlapping region as the highest density region between the region where the toner image 100 for transferability detection is present and the region where there is no toner image (step 201). It is determined whether or not one (step 202). When there is one overlapping area as the highest density area, the CPU 301 or the control circuit 201 determines the one common area as a recommended value (step 203), and ends the recommended value determination flow. If there are a plurality of overlapping areas as the highest density area, as shown in FIG. 20, the minimum value of the common areas is selected and determined as a recommended value (step 204), and the recommended value determination flow is terminated. To do.

  On the other hand, the CPU 301 or the control circuit 201 controls the transferability detection toner image 100 formed on the first surface of the recording paper 26 with respect to the transferability detection toner image 100 formed on the second surface of the recording paper 26. If it is determined that there is no overlapping region as the highest density region between the region with and without the region, it is determined whether there are two or more regions that are determined to have no overlapping region (step 205). When there is only one area determined not to have an area, the one area is determined as a recommended value (step 206), and when there are two or more areas determined not to overlap, The second smallest value in the two or more areas is determined as a recommended value (step 207), and the recommended value determination flow is terminated.

  As described above, according to the above-described embodiment, the transferability detection toner image 100 is formed on the recording paper, and the density of the transferability detection toner image 100 is detected, so that the both sides of the recording paper 26 are detected. The transfer conditions in the case of forming a single color image or a multicolor image so that at least a part thereof overlaps on the front and back can be selected, and the single color image or the multicolor image so that at least a part of both sides of the recording paper 26 overlap on the front and back Can be formed satisfactorily.

Embodiment 2
FIG. 21 shows a second embodiment of the present invention. The same parts as those in the first embodiment will be described with the same reference numerals. In the second embodiment, the second surface of the recording medium will be described. When the plurality of transferability detecting toner images are transferred to the second surface of the recording medium instead of detecting the density of the plurality of transferability detection toner images transferred onto the recording medium, The density of the plurality of transferability detection toner images remaining on the toner is detected by the density detection means.

  That is, in the second embodiment, as shown in FIG. 21, at a position facing the surface of the intermediate transfer belt 21, downstream of the secondary transfer portion along the moving direction of the intermediate transfer belt 21, and cleaning. The density of the plurality of transferability detection toner images 210 remaining on the intermediate transfer belt 21 when the plurality of transferability detection toner images 210 are transferred to the second surface of the recording paper 26 on the upstream side of the apparatus 49 is set. A density sensor 60 as density detecting means for detecting is arranged. For example, the density sensor 60 is the same as the image reading element 11 composed of a CCD or the like of the image reading device 4, but may be any sensor that can detect the density of the transferability detecting toner image 210. Low priced ones are used.

  In the second embodiment, as shown in FIG. 21, since the transfer residual toner images of the plurality of transferability detection toner images 210 remaining on the intermediate transfer belt 21 are detected, automatic density detection is possible. In addition, the effect is particularly obtained when a plurality of transferability detection toner images 210 are likely to remain on the intermediate transfer belt 21.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

  21: Intermediate transfer belt, 27: Secondary transfer roll, 40: Reversing path, 100: Toner image for transferability detection, 205: Operation unit, 314: Manual scanning colorimeter.

Claims (8)

An image carrier for holding a toner image;
Transfer means for transferring the toner image held on the image carrier onto a recording medium;
Fixing means for fixing the toner image transferred onto the recording medium by the transfer means;
A transport unit that transports the recording medium having the toner image fixed on the first surface by the fixing unit to the transfer unit again by inverting the first surface and the second surface of the recording medium;
A transferability detection toner image formed on the first surface of the recording medium and a transferability detection toner image formed on the second surface of the recording medium are combined with the first surface and the second surface of the recording medium. A transferability detecting toner image forming unit that forms a plurality of transfer units with different transfer conditions so that at least a part of the transfer unit overlaps the surface;
Density detection means for detecting the density in both the area overlapping and not overlapping with the transferability detection toner image on the first surface among the plurality of transferability detection toner images transferred to the second surface of the recording medium. When,
And a selection unit that selects a transfer condition in the transfer unit based on detection results in both the overlapping region and the non-overlapping region on the first surface of the density detection unit . Image forming apparatus. The image carrier is composed of an intermediate transfer body onto which a plurality of toner images sequentially formed on a single or a plurality of photosensitive drums are transferred.
The image forming apparatus according to claim 1, wherein the transferability detecting toner image forming unit forms a plurality of transferability detecting toner images with different transfer voltages applied to the transfer unit.   3. The image forming apparatus according to claim 1, wherein the transferability detecting toner image includes a single toner image and a multiple toner image obtained by superimposing a plurality of toner images. The transferability detecting toner image is a multiple toner image obtained by superimposing a single toner image formed on the first surface of the recording medium and a plurality of toner images formed on the first surface of the recording medium. When a single and multiple toner image single toner image partially overlap, which is formed on the second surface of the recording medium formed on the first surface of the recording medium, first the recording medium 4. The image forming apparatus according to claim 1 , wherein the toner image includes a single toner toner image and a multiple toner image formed on the second surface of the recording medium , partially overlapping with the multiple toner images formed on the surface. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the density detecting unit detects a density of the transferability detecting toner image transferred and fixed on the recording medium.   6. The transfer unit according to claim 1, wherein the selection unit selects a transfer condition having the highest density of the transfer image among the densities of the plurality of transferability detection toner images detected by the density detection unit. The image forming apparatus according to any one of the above.   The selection unit is configured to manually or automatically select a transfer condition having the highest transfer density of both the single toner image and the multiple toner image for detecting transferability detected by the density detection unit. Item 7. The image forming apparatus according to Item 6. An image carrier for holding a toner image;
Transfer means for transferring the toner image held on the image carrier onto a recording medium;
Fixing means for fixing the toner image transferred onto the recording medium by the transfer means;
A transport unit that transports the recording medium having the toner image fixed on the first surface by the fixing unit to the transfer unit again by inverting the first surface and the second surface of the recording medium;
A transferability detection toner image formed on the first surface of the recording medium and a transferability detection toner image formed on the second surface of the recording medium are combined with the first surface and the second surface of the recording medium. An image forming apparatus comprising: a transfer property detecting toner image forming unit that forms a plurality of different transfer conditions of the transfer unit so that at least a part thereof overlaps the surface;
Density detection means for detecting the density in both the area overlapping and not overlapping with the transferability detection toner image on the first surface among the plurality of transferability detection toner images transferred to the second surface of the recording medium. When,
A control device comprising: a selection unit that selects a transfer condition in the transfer unit based on detection results in both the overlapping region and the non-overlapping region of the first surface of the density detection unit . An image forming system characterized by that.

Images